A Notable Autumn Arrival of Reverse-Migrants in Southern Nova Scotia Lan Mclaren Grosbeaks.This Was Clearly a Majorevent

Home , Southern Nova Scotia

A Notable Autumn Arrival Of Reverse-Migrants In Southern Nova Scotia lan McLaren Grosbeaks.This was clearly a majorevent. Departmentof Biology, Dalhousie University, Halifax, Nova Scotia B3H 4J1 Althoughmany other birders .had familly commitments the next day,Canadian Thanksgiving, Maybank drove to CapeSable Island BlakeMaybank and met Murray Newell at dawn.The weatherwas still inclement, 144 BayviewRoad, White's Lake, Nova Scotia B3T 1Z1 with northwestgales, overcast skies, and low temperatures,but the KeithKeddy rain had halted.They headedfirst for the site of the previous MeteorologicalService of Canada- Atlantic Region, Environment Canada, 45 evening'sevent and managed to coaxtwo HoodedWarblers from the AlderneyDrive, Dartmouth, Nova Scotia BœY œN6 lobstertraps. Following a hunchthat more species might be found •n PhilipD. Ta¾1or and Trina Fitzgerald nearbysheltered areas of vegetationin the regionknown as The AtlanticCooperative Wildlife Ecology Research Network, Department of Biology, Hawk(Fig. 1), theyinvestigated further and found IndigoBuntings AcadiaUniversity, Wolfville, Nova Scotia BOP 1XO everywhere,including a singleflock with morethan 100 birds There were severalBlue Grosbeaksand Baltimore Orioles,and warblersand ABSTRACT vireosflitted in the aldersand spruces,among them a White-eyed Unprecedentednumbers of apparentreverse-migrant and vagrant Vireo and a Yellow-throatedVireo. Then, in a small hollow sheltered southern birds arrived the afternoon of 11 October 1998 in south- from the gales were four additionalWhite-eyed Vireos, a s•ght ernmostNova Scotia. Their relativeabundances were largely predict- heretoforenever reportedin AtlanticCanada. Among numerous ed by numbersof towerkills recordedduring the fall seasonfrom American Redstarts, Northern Parulas, and Black-and-white 1955to 1980 in northeasternFlorida, as well asby the numberof Warblers,there were an adult male ProthonotaryWarbler, two eachspecies present in Nova Scotiajust prior to the 1998 fallout. ScarletTanagers, and both cuckoos.By this time Newell had to Amongspecies that wereunusually common or scarcerelative to the depart, leaving Maybank to savor another adult male Hooded northwesternFlorida records, excessively large numbers of Scarlet Warbler, another Yellow-throatedVireo, a male Blue-w•nged Tanagers,Blue Grosbeaks, and IndigoBuntings diminished sharply Warbler,a femaleSummer Tanager, and a femaleWestern Tanager soonafter arrival and evidently reappeared in coastalMassachusetts. Curiousto learnif the fallouthad also occurred on neighbonng The manyvireos and warblers lingered, and did not later appearin peninsulaswith a similareast-facing exposure, Maybank headed numbersfurther south.Weather patterns suggest that the birds northeastto BaccaroPoint (Fig. 1), where in lessthan an hour he departedcoastal southeastern United States the evening of 9 October, locateda secondProthonotary Warbler, another Yellow-throated followinga stalledcold front that beganto moverapidly offshore. Vireo,and 10 IndigoBuntings. Blanche Peninsula (Fig. 1) wasnext, Evidentlysome birds reached a southwesterlyflow beyond the front wherehe remaineduntil dusk.Memorable sights there also included andwere carried (and probably flew downwind) to the eastside of a two Blue-wingedWarblers, one White-eyedVireo, and a Golden- deepeninglow southof Nova Scotia.This then propelledthem on wingedWarbler in a singlebush. Other Blanche highlights included easterlygales to a smallstretch of coastand islands at the southern a male HoodedWarbler, a Yellow-throatedVireo, and 70 In&go extremityof the province. Buntings,as well asan immatureHarris's Sparrow that mighthave INTRODUCTION: THE EVENT arrivedwith an influxa fewdays earlier of White-crownedSparrows, On 11October 1998, Nova Scotia was experiencing what locals casu- whichwere still present. ally referto as"weather"-- gale-to-storm-force easterlies, with dri- Other observersmade further discoveries,but Maybank alone ving rain. In late afternoon,Maybank, who then maintainedthe recorded27 individualsof nine speciesthat would normallybe NovaScotia Bird Society Bird Information Line, received a phonecall from Rina Nichols,supervisor of the AtlanticBird Observatory's bandingstation on Bon Portage(Outer) Island(Fig. 1). Sheexcited- ly describedhow, during a just-completed1.5-hour walking census on theisland, observers had tallied 62 IndigoBuntings and 10 Scarlet Tanagers,and manymore in the generalarea. Although such numbers were unprecedented,both speciesare regularhere in late autumnand neitherwould require a rarebird alert.However, it was temptingto speculatewhat other species might be around. Maybank'smusings were cut shortby a phonecall from Murray Newell,a tirelessbirder on CapeSable Island at thesouthern extreme of theprovince (Fig. 1). Newell could not restrainhis jubilation as he reportedwaves of birdscoming in fromthe sea and hitting the coast at Dan'lsHead (Fig. 1) in thelate afternoon. Many birds took shelter in stackedlobster traps, and in one confinedarea Newell and John Nickersonhad encounteredfour HoodedWarblers, a Worm-eating SealI. Ca•SableI. • '• 'TheHawk Warbler, and "many" Indigo Buntings,as well as a few Blue Fig. SeatheraNeva SePia with •lace ,aaes ae,tie,ed i, the te•.

4 NORTH AMERICAN BIRDS Table1. Occurrences of speciesduring the fallout in southernNova Scotia and killed at a northwestFlorida TV tower1-20 October 1955-1980 (Crawford 1985). Numbersfor Bon Portage and Seal islands are combined daily estimates of birdson censusseal areas 11-13 October; numbers in parenthesesare combined counts (if > 0) of thesame species during the three days prior to thefallout, 8-10 October.The "mainland" Nova Scotia count was made 12 October on CapeSable Islandand nearby peninsulas (see text). An asteriskindicates that the species was recorded in theareas of thefallout during the week following 11 October. Speciesmapped in NationalGeographic Society (1999) as breeding no closer to NovaScotia than southern Maine are designated as"(S):' Species BonPortage I. SealI. "Mainland"NS Florida Black-balledCuckoo 0 0 16 Yellow-balled Cuckoo 3 5 2 214 Eastern Wood-Pewee I I 0 8 Yellow-belliedFlycatcher 0 I 0 I '•lradl's"Flycatcher* 0 0 ( I ) 0 3 LeastFlycatcher 0 I 0 0 EasternPhoebe* 0 0 (4) 0 0 GreatCrested Flycatcher 0 0 0 4 White-eyedV•reo (S) 7 8 7 216 Blue-headedVireo 3 (2) 0 (I) I 12 Yellow-throatedV•reo (S) 5 3 6 102 Warblingvireo 0 0 I 0 Ph•ladelphia V•reo 3 ' 0 12 Red-eyedVireo 180(2) 100(4) 32 1374 House Wren 0 I 0 142 Marsh Wren I 0 0 88 Ruby-crownedKin•let 22 ( I •) 68 ( 15) 2 93 Veery I (I) 0 0 177 Gray-cheekedThrush 0 0 0 98 Swainsoh'sThrush 0 0 I 280 Hermit Thrush 0 3 0 29 Wood Thrush 0 0 0 213 GrayCatbird 10 13(4) I 662 Brow• Thrasher 0 0 0 187 Blue-w•ngedWarbler (S) 0 I 4 25 Gold?-wingedWarbler (S) I 0 i 19 TennesseeWarbler 6 2 0 345 Orange-crownedWarbler* 0 0 0 6 Nashwlle Warbler 0 7 0 2 N. Parula 52 20 19 457 Yellow Warbler 0 I 0 18 Chestnut-s•dedWarbler 13 7 I 305 Ma•nohaWarbler 14 (2) 21 (2) 9 430 CapeMay Warbler I 0 0 II Black-throatedBlue Warbler 2 (5) 0 2 17 Yellow-rumpedWarbler 190(57) 220 ( 125) 50 4 Black-throatedGreen Warbler 13 19 (2) 4 40 Blackburn•anWarbler 2 I 0 105 Yellow-throatedWarbler (S) 4 I 0 •5 Pine Warbler* 0 0 0 54 PrairieWarbler* (S) 0 0 0 134 PalmWarbler 19(3) 15 (2) 2 i 506 Bay-breastedWarbler I 0 0 25I BlackpollWarbler 6 (8) 8 (3) 5 J CeruleanWarbler (S) 0 0 0 I Black-and-whiteWarbler 22 45 4 224 AmericanRedstart 91 77 (8) 17 473 ProthonotaryWarbler (S) 0 0 2 3 Worm-eatingWarbler (S) 0 I 0 4 I ;wmnson'sWarbler (S) 0 0 0 35 Ovenbird 20 (4) 31 2 436 Northern Waterthrush 4 õ 0 179 LouisianaWaterthrush (S) 0 0 0 3 KentuckyWarbler* (S) 0 0 0 38 Connecticut Warbler 2 0 0 0 Mournin• Warbler I 0 0 0 CommonYellowthroat 125( I I ) 163(9) 6 824 HoodedWarbler (S) 8 2 4 320 Wdson's Warbler 0 2 I I Canada Warbler* 0 0 0 4 Yellow-breastedChat* (S) 0 0 0 28 SurnmerTanager(S) 0 0 I 88 ScarletTanager 31 5 5 98 Rose-breasted Grosbeak I 3 0 55 BlueGrosbeak (S) 27 31 6 27 IndigoBunting 255 102 190 57 I OrchardOriole (S) 0 0 0 I Bafarnore Oriole 0 0 2 8

VOLUI•E54 (ZOO0), #UI•BER ! ß ß

BIRDING TOURS WORLDWIDE

Day in October 1998 Fig.Z. Numbersof birdsof certainspecies or speciesgroups of birdsestimated in dailycensus areason BonPortage and Seal islands, NS, October 1998. The "warblers"in panela) exclude November10-26, 2000 Yellow-rumped("Myrtle") and Palm Warblers. The species in panelb) are:Yellow-rumped withJan Pierson & ChrisKightley Warbler(MYWA), Palm Warbler (PAWA), and Ruby-crowned Kinglet (RCKI). The species in panelc) Comfortabletour visiting three of Brazd's finest are IndigoBunting (INBU), Blue Grosbeak (BLGR), and Scarlet Tanager (SCTA). locales,each world-famous for anabundance of birdsand wddlife ma spectacularsetting right reportedto local rare bird alerts,some of them (E Lavenderpers. comm.). However, outsideour doors; also an 0vemight inRio. whichwould require documentation. (And around Little Harbour, some35 mi (60 km) that excludes the remarkable count of northeastof Cape SableIsland (Fig. 1), HOLIDAYSAT SAN ISIDRO, DavidYoung (pets. comm.) found about 20 ECUADOR almost200 IndigoBuntings.) November17-26, 2000 with Mitch Lysinger Throughthe week the teamson Bon Red-eyedVireos and the followingvagrants December23, 2000-January 1, 2001 Portageand Seal islandscontinued their in four hourson 12 October:a White-eyed withMitch Lysinger bandingand standardizedcensussing, and Vireo, a Blue-winged Warbler, a Blue Bird-richThanksgiving orChristmas escapes, were astonishedby peak daily estimates Grosbeak,and an Indigo Bunting.There basedprimarily atthe very comfortable SanIsidro totaling over 500 warblers and vireos, were no reportsof vagrantsnortheast of Lodgeaka Cabarias San lsidro). includingup to 24 southernvagrant indi- thisarea during the nextfew days. A weaker and later fallout event NEW GUINEA & AUSTRALIA viduals among them. Interestingly, occurred in coastal Massachusetts. November18-December 6, 2000 althoughScarlet Tanagers, Blue Grosbeaks, with John Coons and Indigo Buntings continued to be Numbersand datescan be gleanedfrom Arich and diverse sampler ofthe best b•rdmg of abundant,their numbersdeclined sharply Ellison and Martin (1999) and Rineset al. NewGuinea and Australia, including Ambua afterthe firstday. (1999),and most thoroughly from newspa- Lodgeand O'Reilly's. The cornucopiapoured out all week. per accountsby E. VernonLaux (Vineyard TRINIDAD & TOBAGO Maybank returned 16 October with Gazette: 23 November 1998, "Bird notes;" November 23-December 2. 2000 McLaren, Eric Mills, and Elizabeth 30 November 1998, "Autumn Storm Leads withWayne Petersen Stockwe!!.The weatherwas again blustery, to Rare Bird Landings"). The earliest December27, 2000-January5, 2001 but the birdscontinued to delightat most reported Indigo Buntingswere eight at withDoug McRae spots searchedearlier in the week by Truro, Cape Cod, 12 October;others were Wonderfulintroduction to SouthAmerica's bird foundthat day on Martha'sVineyard, along riches,from Scarlet Ibis to wonderfulbellbirds Maybank(although the party did not visit with nine Blue Grosbeaks. Greater numbers anddazzling manakins. BaccaroPoint due to lackof time). Despite dailyobservation by othersin the interim, of Blue Grosbeaksappeared later on new discoveries were still made, and the Martha'sVineyard: 16 on 14 Octoberand morethan 100 departures worldwide. party found several RBA-reportable 26 on 16 October. There is no mention of species,including six White-eyedVireos, largenumbers of northernvireos and war- 800-728-4953 three Yellow-throated Vireos, a Golden- blers,but southernvagrants included a winged Warbler, a Yellow-throated White-eyedVireo at Truro on 12 October, fieldguides INC. Warbler,two KentuckyWarblers, and four and four-fiveScarlet Tanagers, a Yellow- 9433 BEE CAVE ROAD, male Hooded Warblers. throated Vireo, and a Yellow-throated BUILDING 1, SUITE 150, The extraordinarymagnitude of the Warblerand threeProthonotary Warblers AUSTIN, TX 78733 fallout was evident to all who witnessed it. during 13-14 October. Two Hooded FAX 512-263-0117 For comparison,between 1964 and 1997 Warblers were netted at Tuckernut on 12 http://www.fieldguides.com October.The only publishedmention of a fieldguides@fieldguidescorn on 144birding days on SealIsland during the first 20 daysof October,none of the timelyoccurrence in relationto the Nova above-mentionedmaximal day counts was Scotia arrivals were the four Blue Grosbeaks ¾ F exceeded(many observers,from unpub- found11 October on BlockIsland, RI, quite lisheddaily lists collectedby McLaren). far from the storm's center (Ellison and The 1998 falloutwas notablyfocused on Martin 1999). '1 east-facingareas of southernmostNova THE LIST Scotia. To the northwest, no unusual num- Estimated numbers of individuals of the bersof migrantsand vagrants were report- variousspecies involved in the fallout in ed during the week of ll Octoberfrom NovaScotia have been publicized previous- activelybirded locations around Pubnico ly (Brinkley 1999, Ellison and Martin, andYarmouth (Fig. 1 ). Morepertinently, a 1999).Those numbers were generated by l•o ß o _,rea ,'st', NovaScotia Bird Society field trip on Brier Maybank partly by extrapolationsfrom to oo /rob, Island (Fig. 1) found many birds 11-12 reportsthat concentratedonly on rarities October,but no southernvagrants among and vagrantsto estimatenumbers of more

6 NORTH AHERICAN BIRDS NOVA SCOTIA common species.Maybank had also used BlueGrosbeaks, like tbis one countsmade by variousobservers through sitting in a sprucein southern the week followingthe fallout, when there Nova Scotia in mid-November were considerablechanges in relativeabun- 1995, are scarcevagrants in danceofthe fallout species. the province;more than GO In thecombined daily estimates in cen- duringthe first three daysof sussedareas of Bon Portage and Seal islands, the fallout in October 1998. abnormallylate migrant and vagrantwar- blersand vireos (along with a handfulof fly- catchers, thrushes, and Gray Catbirds) The most abundant "southern" peakedon 12October, the dayafter the storm Warbler in the 1998 fallout (Fig.2a). By contrast, the notable numbers of wasthe Hooded,most of IndigoBuntings, Blue Grosbeaks, and Scarlet them males like this one Tanagersdropped sharply (Fig. 2c). Three glowingamidst building abundant,hardy species that normallyhave debris on Sable I. in peak abundancesin Nova Scotiain early mid*September1974. October or later (Tufts 1985)--Ruby- crowned Kinglet, Yellow-rumpedWarbler (which also winters in numbers) and Palm Warbler(Fig.2b)-•continued toincrease for A few IndigoBuntings, like this somedays after the storm. one on SealI. in October1987, Forfurther analysis, we used only the esti- are regular late-fall vagrantsin mateddaily numbers of eachspecies in the NovaScotia, but occurredin islandcensus areas 11-13 October,along unprecedentednumbers as the with numberstallied by Maybankduring his mostabundant species in the 1998 fallout. extensivesurvey 12 October.We excluded somesparrows that areroutine, often in large numbers,at this time of yearand that also winter in Nova Scotia;those speciesgenerally reckoned as day- Bobolink).The final lists(Table 1) representrelative abundances of migrantsor otherwiseunlikely to haveflown offshore further south the speciesthat arrivedin the fallout. (other sparrows,most icteridsother than orioles;the western SPECIES COMPOSITION AND vagrantsWestern Tanager and Harris'sSparrow); and those not ORIGIN OF THE BIRD5 notedamongst trees and brushthat were searched(swallows and Herewe usethe relativeabundances of the falloutspecies in Table1

TheGrand Prize winnerand a companionwill receiveprivate tours led by top birdersfrom Victor Emanuel Nature Tours and Fermata, Inc. Foodand lodgingare alsoincluded. Six otherwinners will also be drawn to each receive a free weekend at one of the followingcharming accommodations locatedin prime birdingareas: The inn at Chachalaca Bend, Los Fresnos The Inn at El Canelo0Raymondville The Queen Anne Bed & Breakfast,Galveston Island HoopesHouse Bed & Breakfast,Rockport The Brown Pelican Inn, South Padre Island CaymanHouse Bed & Breakfast,Rockport

Texas offers some of the best birding in the country. So we decided to offer "The Texas Birdwatching Bonanza" - an Entryfees are $10 per person. exciting opportunity to win a package of three spectacular All proceedswill fund TexasParks and Wildlife Texas birdwatching trips. arian habitat conservationprojects. For more informationor to receivean entry form, call Lower Rio Grande Valley Specialties toll-freeat BBB-TX-BIRDS(B924737) or visit us Spring Migration in the Upper Texas Coast and Pineywoods on the web at: www.tpwd.state.tx.us/bonanza Migrants and Hummingbirds of the Davis Mountains and Big Bend Region TEXAS PARKS AND WILDLIFE

VOLUME54 (ZOOO)tNUMBER I 7 as an indication of their possibleorigin. Clearly some species produceswell-fitting models. Almost one-third of the variation(r-' = markedas "southern" in TableI had undergonereverse migration 0.29)in thecombined Nova Scotia counts is predicted by the Florida from somewheresouth of New England;presumably some associat- countsalone (t = 5.25,P <<0.001). However,some of the presumed ed specieshad alsodone so. South of New England,a "goodflight" falloutbirds were obviously in the vicinitybefore 11 October.To of warblerswas in coastalVirginia 23 September1998 (11iff1999), correctfor the expectedpresence of suchindividuals during 11-13 and a few concentrations were also found in the southern Atlantic October,we alsoused models that includedthe averageabundances Statesin September(Davis 1999).By earlyOctober, however, most (log [n + 1]) of all speciesthat hadbeen detected in the threedays warblerspecies would have vacated the mid-Atlantic states while still prior to 11 October on Bon Portageand Seal islands(Table 1). showingpeak or near-peaknumbers in Floridaor on theGulf Coast Understandably,this sharplyincreased the amount of variation (Dunn and Garrett 1997). Indeed, there were notable numbers of explained(r 2 = 0.53), but slightlyweakened the relationshipof the vireosand warblersin Floridaduring late Septemberand early falloutand Florida estimates (t = 4.91).Similar models fit separate- October1998 (Pranty 1999). Local banding records may be uninfor- ly to the datafor eachisland (no pre-falloutestimates available for mative.For example,on a capturelist of 22 speciesfrom Orlando, the mainlandcounts) increased the amountsof variationexplained FL, 10-12 October(Parks Small, Florida Park Service, pers. comm.), (• = 0.56 for Bon Portage,r2 = 0.52 for SealIsland), but the rela- only the CommonYellowthroat was amongthe top ten in found tionshipbetween the falloutand Floridaabundances was strength- NovaScotia (Table 1). Many of the falloutspecies also occur in the enedonly for BonPortage Island (t= 5.88for Bon Portage,r• = 4.63 fall on the Bahamas.There are no quantitative recordsavailable from the Bahamasfor early October 1998 (Rick Oliver and Tony White, pets.comm.), and recordsof killsat twotowers on Grand Bahama22 October 1966 (Kale et al. 1969)do not seemhelpful; among 133 individualsof 22 species,more than half consistedof Gray-cheeked Thrushes (39), Blackpoll Warblers(21) and NorthernParulas (14), only the last of which was amongthe top ten in Nova Scotia. Without sufficient combined records of numbersfrom bandingstations or otherquan- titative lists from southeastern U.S. at the time of the fallout, we use the extensive data in Crawford (1981a). He presentednumbers killedat a northwestFlorida TV towerduring the three 10/11-day periods of each month from 1955 to 1980. From these we combined the countsfor the first two 10-dayperiods of October. As with the Nova Scotia list (see EnhanceYour Life List above),we includedonly those species that are primarilynight migrantsand excludedthose Showcasebirdin accomplishments whilecrcatin a that routinelywinter in NovaScotia. Of the 10 treasuredheirloom mostabundant species in the Nova Scotiafall- out (Table 1; estimates>80), six wereamong The heartof yourbirding activities is your life list. How do you preserve the top 10 in Florida.Among the NovaScotia yourexperiences? Designed to lasta lifetime,Life-List Illustrated top 10,all had peakFlorida mortalities during enablesyou to transformyour field guide checkmarks into the first third of Octoberexcept for Red-eyed fully-illustratedjournal entries. Vireo,which had peaksin the firstand second third periods(differing age groups?). ß Fieldsfor color labelsand notes The similarityof the rankedabundances at • • ,•, printedonarchival paper the three Nova Scotialocations (R s = 0.66•0.77 ß. •_.t .• • ß Morethan %000 full-color illustrated in the threecomparisons, all P <<0.001) is as • "• ß '• labelsshowing accurate field markings expected.The high correlationof the com- .1 % . Sectionsto record birds of the 48 bined Nova Scotiaestimates with thosefrom • contiguousstates, Alaska, and Hawaii Florida (r • = 0.51, P <<0.001) is also not sur- prising,as the samewould probably be true of ,,, . Sectionto recordthe officialbirds and anyother pair of substantialautumn lists from greatseals of the5o United States easternNorth America.Of greaterinterest is • ß Birdindex updated to the•999 AOU the extent to which observedspecies abun- ----•'" / checklist dancesin NovaScotia can be explainedby their Theleather-trimmed cloth-lined journal opens on piano hinges and is protected relativenumbers at that time in Floridaand by bya hardcover slipcase to create a timelessdisplay for you and others to enjoy. other possibleinfluences. Regressions using raw numbers (Table 1) have severestatistical Li½-List ,12o.ooplustaxand shipping problems,with residualsfar from normal ILLUSTRATED (Kolmogorov-Smirnovtests, P <<0.001). Logarithmictransformation of numbers(+1)

8 NORTH AMERICAN BIRDS NOVA SCOTIA

cold front '- warmfront for SealIsland). A surprisinglylarge amount of variationamong the w*nd (knots) falloutspecies can thusbe explainedby expected"background" •5 numbers and the Florida tower kill records. Regressioncan also incorporate features that mightreflect the ab]ht]esof speciesto undertakeor survivesustained flight over the ocean.We hypothesized asadditional independent variables: migra- tionspan, crudely as the difference between median latitude of sum- mer and winter ranges(from Howell and Webb 1995;National 1012 GeographicSociety 1999; Ridgely and Tudor 1989, 1994); average or medianwing length (from Pyle 1997); average body weight (mostly fromDunning 1993); and interactions among them. The only vari- I0 Oct.,OOZ able,along with the pre-fallout counts, that added slightly to amount of variationexplained (r 2 = 0.55) and to the relationshipbetween the Nova Scotiaand Florida abundances(t = 5.21) after stepwise regression,was body weight (t = -1.88,P = 0.063).This seemingly counterintuitive,weakly negative effect of bodyweight appears to reflectconsistent under-representation of the relatively large thrushes and mimids,not compensatedby over-representationof fewer largespecies like Blue Grosbeak. Probablythe mostreliably counted birds were the vireosand warblers,which occurredin similar woodedhabitats, often flocked together,and were keenly sought. The towerkills for thisselected group,along with the average abundances onthe islands prior to the fallout,indeed explain more variation (r 2 = 0.68, t = 4.99 for the effectof theFlorida counts) among the fallout abundances, with no othersignificant variables. The model using data from Bon Portage Fig. 3. Surfaceatmospheric pressure and wind patterns9-11 Islandalone explained no moreoverall variation in falloutnumbers October1998. Thewind directions, where strong, probably (r2 = 0.66),but enhancedthe apparentexplanatory power of the reflectquite well thoseat highereltitudes, where birds Floridacounts (t = 6.19).Use of datafrom Seal Island alone greatly migrate.The universal times (Z), 00, IZ, and18, ere equive- increasedthe amountof variationexplained in falloutnumbers (r 2 lent to ZI:00, 09:00, end 15:00 ADTrespectively in Nova = 0 72), largelyattributable to theprior islandcounts (t = 7.21vs. Scotia,and one houreerlier in Florida. 4 84 for the effectof Florida counts). CapeCod in the northto acrossnorthern Florida in the south.The G•venthe variationsamong the variousmodels, it wouldbe frontwas embedded in a shallowtrough, with cyclonicflow begin- unwiseto aftemptto explainall remainingdifferences between the ning to developat its northernend, and movedsharply offshore NovaScotia and Florida lists. In statisticalterms, only the regression overnight9-10 Oct. (Fig. 3, 10October, 00 Z and12 Z). ^lthoughthe for all specieson Table1, usingboth pre-falloutabundances and coldfront was weak, with following surface flow only N5 knots in the bodyweights,had a speciessignificantly too common in NovaScotia southeasternUnited States, these conditions generally encourage relauveto FloridaThis was the Indigo Bunting (standardized resid- migration.As Richardson(1972) found from radar studies in east- ual = +3.54), with the Blue Grosbeak(+2.79) and then Scarlet ern Canada:"Offshore flights to the SEor S weremost common or Tanager(+1.97) next most deviant, although not significantly so (at densestwhen therewere W or NW winds.Such winds usually P = 0 05).These deviations do not detractfrom the general conclu- occurredimmediately after the passageof coldfronts." Richardson sionthat the fallout originated from an assemblage of species resem- (1976)also found that landbirds flying toward the WestIndies gen- bhngthe set of birdsusually present at thesame season in thesouth- erallycontinued southeast-south-southwest at dawn even over the eastern United States sea. Southeast movement of birds on 5-knot northwest winds with WEATHER PAl'tERNS AND passageof a coldfront is pertinentlyevident in grounddistribution ORIGIN OF THE BIRDS of bird kills at a TV tower at the Tall Timbers Research Station in The easterliesthat brought the birds ashore were associated with LeonCounty in theFlorida panhandle (Crawford 1981b, his Fig. 1, deepeninglow pressure centered south of NovaScotia and east of depicting25 September1965). On the otherhand, ahead of such CapeCod (Fig. 2, 11October, 18 Z, 13:00ADT). Thelack of fallout cold frontswhere southwestflow prevails,there can be reverse, in localitiesin thewind "shadow" to thenorthwest (Fig. 1), is in downwindmigration, although this is variablein occurrenceand keepingwith this pattern. The fewer birds around Little Harbour, intensity(Richardson 1978, 1982). NS (Fig.1), andlack of recordedsightings beyond that to the Thus,a largemovement of birdsoff the southeastU.S. coast northeastalso indicate that a quitecompact mass of birdshad couldhave occurred on thenight of 9-10 October.The slackness of becomeentrained dose to the storm'scenter (see the isobarpat- winds(6pen isobars on Fig.3) southeastof Floridamight suggest ternsFig. 3, 11October, 18 Z). Thelimited number of species, thatmass departures would not haveoriginated from the Bahamas. smallernumber of individuals,and evidently later appearances of However,there was also strong convection (cumulus and thunder- apparentfallout species in coastalMassachusetts (see Introduction) storms)over the Bahamasthat couldhave carried birds aloft. North suggestthat those were birds that had resumed southward migra- of the Bahamasthe strongsoutherly flow in thewarm sector could uonfrom Nova Scotia. This hypothesis isreinforced by the sharp havetriggered downwind, reverse migration by offshoremigrants. diminutionof numbersof BlueGrosbeaks and Indigo Buntings the Moreinsight can be gainedtracking hypothetical parcels of air dayafter the Nova Scotia fallout. usingthe Canadian Meteorological Centre's trajectory model. Back- Wheredid theyoriginate? In earlyevening Oct. 10 (Fig.3, 10 trajectoriesof air arrivingat Cape Sable(Fig. 1) at 12 Z proved October,00Z) andfor morethan 24 hourspreviously, a characteris- somewhatunrevealing. Parcels at 1000(surface) and 925 hPa (N0.5- t•c"Carolinasfront" was nearly stalled along the U.S. east coast, from mile altitude) arrivedfrom the northeast.However, air at 850 hPa

VOLUME54 (zooo), NUMBERI 9 Fig. 4. Trajactoryof an imaginaryparcel Scotia,which ultimately propelled them ashore. Such centers usual- of air originatingat ly moverapidly to the northeastand offshore,and must on such Freaport,Bahamas, occasionscarry many more landbirds to a wateryend. A plausible and tracked over the case has indeed been made that severe North Atlantic storms in next three to four autumnmay negatively influence songbird breeding populations the days.Positions each followingspring (Butler 2000). The arrival of muchgreater numbers dayat 12 Z, or 08:00 of IndigoBuntings, Blue Grosbeaks, and Scarlet Tanagers relative to in Freeportand theirabundances on the Florida list may indicate that they were bet- Og:00 ATD in Nova ter ableto sustainthe long flight. The sharp drop in theirnumbers Scotia,are indicated. the day after arrivaland their apparentreappearance in coastal Massachusettsmay also reflecta robustcondition for resumed migrationcompared with themany, mostly smaller, obligate insech- votes.More insightson effectsof the 1998 fallout and simdar reverse-migrationevents could be gainedby analysisof banding recapturerates and changes of bodycondition of individualsof the speciesinvolved. ACKNOWLEDGMENTS We are gratefulto RobertCrawford for supplyinga copyof his valuable (-1 mile up) was traceableto a positionMOO miles north of analysisof tower kills in Florida (Crawford 1981a), to Jim Abraham of Bermuda24 hoursearlier. Passerines in the Caribbeanregion can EnvironmentCanada for meteorologicalinsights, and to the observerson certainlyfly at suchheights (Richardson 1976), but Bermudais a CapeSable and those with theAtlantic Bird Observatory, who first alerted us mostunlikely origin of the fallout. to the ensuingspectacle and obtainedvital data on its nature.We thank DouglasMcNair and RichardVeit for usefulcomments on the manuscript Anotherapproach is to traceforward-trajectories from plausible LITERATURE CITED sources.A hypothetical origin from Bahamas (Fig. 4) isrevealing. For Brinkley,E.S. 1999. Changing seasons: fall migration.North American B•rds birdsto haveleft Freeport,convected locally to 925-850hPa (0.5-1 53:12-19. mile) levels,and then to be carriedpassively to NovaScotia by after- Butler,R.W. 2000. Stormyseas for someNorth Americansongbirds are noon11 October,would have required departure almost a half-day declinesrelated to severestorms during migration.* Auk 117:518-522 prior to 9 Octoberat 12 Z (the eveningof 8 October).This would Crawford,R. L. 1981a.Bird casualties at a LeonCounty, Florida TV towerA havemeant staying aloft almost three days. However, the Freeport air 25-yearmigration study. Bulletin of theTall Timbers Research Station 22 Crawford,R.L. 1981b.Weather, migration and autumnbird killsat a North parcelwas greatly accelerated at thesealtitudes beginning next day Florida TV tower. Wilson Bulletin 93:189-195. (Fig.4). Passerinesdeparting east to southeaston the eveningof 9 Davis,R. 1999.Southern Atlantic coast region. North American Birds 53:43-45 Octoberfrom the Carolinasto Floridaand traveling at flightspeeds Dunn,J. and G. Garrett.1997. A FieldGuide to the Warblers of North America of -20-25 m.p.h.could easily have been 200 milesoffshore at dawn HoughtonMifflin, Boston. thenext day (Ehrlich et al. 1988).This would have placed them near Dunning,J.B. 1993. CRCHandbook of Arian Masses. CRC Press, Boca Raton Ellison,W.G. and N.L. Martin 1999.New Englandregion. North American dawnon 10 Octobersomewhere between the hypothetical positions Birds 53:30-34. (Fig.4) of theBahamas air parcel at 12Z on9-10 October.The accel- Erlich,P.R., D.S. Dobkin and D.Wheye.1988. The Birder's Handbook. S•mon eratedsouthwest flow would then havetaken them quite closeto and Schuster,New York. NovaScotia by earlymorning 11 October (Fig. 4). Abettedby down- Gauthreaux,S.A., and K.P.Able. 1970.Wind directionand directionof noc- wind flight,an arrivalin southwestNova Scotia a fewhours later, less turnalsongbird migration. Nature 228:476-477. thantwo days after departure, ishighly plausible. It is also noteworthy Howell,S.N.G. and S. Webb. 1995.A Guideto the Birdsof Mexicoand that the hypotheticalair masses,after reaching Nova Scotia, did not NorthernCentral America. Oxford University Press, New York. Iliff, M.J.999. Middle Atlantic coast region. North American Birds 53:39-43 passnear coastal Massachusetts (Fig. 4). Kale,W.H., II, M.H. Hundleyand J.A. Tucker. 1969. Tower-killed specimens It is alsopossible that meteorological conditions had concentrat- and observationsof migrantbirds from GrandBahama Island. Wdson ed the birdsat departuresites prior to their offshoremovements. Bulletin 81:258-263. There were broad south-southeast airflows in the southeastern McLaren,I. A. 1981.The incidenceof vagrantlandbirds on NovaScotJan UnitedStates in advanceof the progressingfront beforeit reached islands. Auk 98:243-257. the coast.If manysuch migrants had orienteddownwind, as noted NationalGeographic Society. 1999. Field Guide to the Birds of North America NationalGeographic Society, Washington, D.C. previouslyat sitesin Louisianaand Georgia by Gauthreauxand Able Pranty,B. 1999.Florida region. North American Birds 53:46-48. (1970),they might have become concentrated along the front as it Pyle, P. 1997. IdentificationGuide to North AmericanBirds, Part 1 progressed.However, this in itselfcannot explain the arrivalof such Columbidaeto Ploceidae.Slate Creek Press, Bolinas, California. largenumbers from offshorein NovaScotia. Richardson,W. J. 1972.Autumn migration and weather in easternCanada a CONCLUSION radarstudy. American Birds 26:10-17. Richardson,W. J. 1976.Autumn migration over Puerto Rico and the western It is clearthat the largeand diverseassemblage of birdsthat arrived Atlantic:a radarstudy. Ibis 118:309-332. at southernextremity of NovaScotia from the eastoriginated much Richardson,W.J. 1978. Timing and amount of bird migrationin relationto farthersouth, plausibly from the southeasternU.S., 1500-2500km weather: a review. Oikos 30:224-272. distant.This contrastswith Richardson(1982), who could not con- Richardson,W.J. 1982. Northeastward reverse migration of birdsover Nova dude from radar trackingthat autumnreverse migrants in Nova Scotia, Canada, in autumn. BehavioralBiology and Sociobiology Scotiahad traveled more than 400 km fromNew England. The com- 10:193-206. bination of offshoremovements of cold fronts in the southernU.S., Ridgely,R.S. and G. Tudor.1989. The Birds of South America, vol. 1. University of TexasPress, Austin. with low pressuredeveloping farther north, is a commonmeteoro- Ridgely,R.S. and G. Tudor. 1994. The Birds of South America, vol. 2. University logicalpattern, and may help explainthe unusualfrequency of of TexasPress, Austin. southernvagrants during autumn on NovaScotia islands (McLaren Rines, M.W., S.A. Perkins,and R.H. Stymeist.1999. Bird sightings 1981).The particularly spectacular example of 11October 1998, after September-October.Bird Observer 27:33-53 thebirds became caught up in southwesterlyflow, may have resulted from the slow movement of the storm center off southern Nova Tuffs,R.W. 1985. TheBirds ofNova Scotia, 3rded. Nimbus Publishing acd --ReceivedNovaScotia7February Museum, 2000,Halifax. Accepted 5July 2000 •½i•. 1o NORTH AMERICAN BIRDS